1. PHYSICS – Mass and Weight

2. LEARNING OBJECTIVES 1.3 Mass and weight Core Show familiarity with the idea of the mass of a body State that weight is a gravitational force Distinguish between mass and weight Recall and use the equation W = mg Demonstrate understanding that weights (and hence masses) may be compared using a balance Supplement Demonstrate an understanding that mass is a property that ‘resists’ change in motion Describe, and use the concept of, weight as the effect of a gravitational field on a mass

3. Mass, weight and gravity ‘g’ actually has two meanings:  g is the acceleration of free fall (10m/s 2 )

4. ‘g’ actually has two meanings:  g is the acceleration of free fall (10m/s 2 )  g is the gravitational field strength (10N/kg) Mass, weight and gravity

5. Gravitational field strength is the force experienced by a mass due to gravitational attraction. Mass, weight and gravity

6. Gravitational field strength is the force experienced by a mass due to gravitational attraction. Weight is the term we use for the Earth’s gravitational force on an object. Mass, weight and gravity

7. Weight = mass x g (where g = 10N/kg) Mass, weight and gravity

8. Weight = mass x g (where g = 10N/kg) W = mg Mass, weight and gravity

9. Weight = mass x g (where g = 10N/kg) W = mg W = 1000 x 10 Mass, weight and gravity

10. Weight = mass x g (where g = 10N/kg) W = mg W = 1000 x 10 W = 10,000N Mass, weight and gravity

11. Weight = mass x g (where g = 10N/kg) W = mg Remember: mass doesn’t change – it’s the gravitational force that may change Mass, weight and gravity

12. MassWeight In space 1000kgZero On the Mooon 1000kg1,600N On Earth 1000kg10,000N Mass, weight and gravity

13. Mass 500kg 6000N upward force from rocket engine Weight

14. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket?

15. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket? W = mg

16. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket? W = mg W = 500 x 10 = 5000N

17. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket? W = mg W = 500 x 10 = 5000N Resultant force upwards = upwards force – downwards force

18. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket? W = mg W = 500 x 10 = 5000N Resultant force upwards = upwards force – downwards force = 6000 – 5000 = 1000N

19. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket? W = mg W = 500 x 10 = 5000N Resultant force upwards = upwards force – downwards force = 6000 – 5000 = 1000N Resultant force = mass x acceleration

20. Mass, weight and gravity Mass 500kg 6000N upward force from rocket engine Weight What is the acceleration of the rocket? W = mg W = 500 x 10 = 5000N Resultant force upwards = upwards force – downwards force = 6000 – 5000 = 1000N Resultant force = mass x acceleration 1000 = 500 x a 1000 = a 500 Acceleration = 2 m/s 2

21. LEARNING OBJECTIVES 1.3 Mass and weight Core Show familiarity with the idea of the mass of a body State that weight is a gravitational force Distinguish between mass and weight Recall and use the equation W = mg Demonstrate understanding that weights (and hence masses) may be compared using a balance Supplement Demonstrate an understanding that mass is a property that ‘resists’ change in motion Describe, and use the concept of, weight as the effect of a gravitational field on a mass

22. PHYSICS – Mass and Weight